The present invention relates generally to antimicrobial compositions and, more particularly, to improved antimicrobial compositions including an enhancing, potentiating or synergistically effective component. The inventive compositions are particularly useful in disinfecting and cleaning applications, such as the disinfecting and cleaning of hard surfaces.
Disinfecting compositions which include a variety of active disinfecting components, such as aldehydes, glycols, amines and quaternary ammonium compounds, are known. For example, laid-open patent application specification, DE 195 23 320 A1, of Bode et al., discloses a disinfecting concentrate which contains such disinfectants, conventional additives, water, and one or more terpenes in a particular concentration, namely, 0.1 to 50 percent by weight relative to the concentrate. The terpene additive is said to enhance the efficacy of the disinfectants in the concentrate. The concentrate is disclosed as being useful for the disinfection of instruments, for disinfection in the presence of mycobacteria and certain viruses, and, upon dilution, for the disinfection of surfaces. While Bode et al. disclose a variety of terpene additives, they do not disclose the sesquiterpene alcohol, nerolidol, as being useful in their disinfecting concentrate.
In U.S. Pat. No. 5,135,743, Stanislowski et al. disclose a composition for deodorizing animal wastes in which a liquid dispersion of pine oil and boric acid act to prevent ammonia formation. Adjunct materials, such as quaternary ammonium compounds, can be included in the composition. The pine-oil component is said to be a complex blend of a variety of organic compounds, including terpenes. Stanislowski et al.""s pine-oil component does not contain nerolidol, however, as this particular sesquiterpene alcohol is not derived from pine oil.
In U.S. Pat. No. 4,867,898, Spaulding et al. disclose a liquid, hard-surface cleaner, which contains pine oil, but no quaternary ammonium compounds. Spaulding et al. teach against the use of quaternary ammonium compounds in cleaners because of the undesirable qualities of these compounds, such as high residue deposition after cleaning, toxicity, and irritation to a user""s skin, eyes, and the like. As with Stanislowski et al.""s pine-oil composition, Spaulding et al.""s pine-oil cleaner does not contain nerolidol.
U.S. Pat. No. 4,540,505 to Frazier discloses that cleansing agents containing a germicidally effective quaternary ammonium compound are known, as are cleansing agents containing the terpene derivative d-limonene. However, Frazier discloses that when even a small amount of d-limonene is introduced into a composition having a cleansing agent containing a quaternary ammonium compound, the composition is destabilized. Thus, Frazier discloses a composition including monoethers of certain aliphatic glycols to provide composition clarity and stability.
In U.S. Pat. No. 4,113,709, Quinlan discloses certain polymers of quaternary thiazines as being useful for a variety of applications, including the inhibition of corrosion. Quinlan further discloses that these polymers may be blended with known acid inhibitors, such as quaternary ammonium compounds or synergists, which may include terpene alcohols. Use of the term xe2x80x9csynergistxe2x80x9d is not explained.
Nerolidol is not disclosed in any of the above-referenced patents. It is disclosed, however, in relation to various oral compositions in a number of United States patents. For example, U.S. Pat. No. 5,116,602 to Robinson et al. discloses nerolidol as a sesquiterpene alcohol flavor component in an oral antiplaque composition. The flavor component is said to provide antimicrobial activity at low concentrations.
U.S. Pat. No. 5,256,401 to Duckenfield et al. discloses nerolidol as an effective antiplaque agent in a mouthwash composition. The effectiveness of the substantially water-insoluble antiplaque agent is said to be attainable without the excessive presence of solvent to solubilize the agent and without the use of an antibacterial-enhancing agent.
As a further example, U.S. Pat. No. 5,424,059 to Prencipe et al. discloses nerolidol as a water-insoluble, non-cationic antibacterial agent useful in an antiplaque dentifrice. The effectiveness of the antibacterial agent is said to be enhanced by xylitol.
Finally, U.S. Pat. No. 5,575,652 to Gaffar et al. discloses that both non-cationic antibacterial agents and cationic antibacterial agents, such as quaternary ammonium compounds, have been investigated as antiplaque agents. Gaffar et al. note that while the non-cationic agents can be compatible with anionic components, the most investigated of the cationic agents have proved to be generally ineffective when used with anionic materials in an oral composition. They thus disclose nerolidol as a water-insoluble, non-cationic antibacterial agent useful in an oral gel composition applied to dental implant sites. The effectiveness of the antibacterial agent is said to be realized when the agent is solubilized in the presence of an antibacterial-enhancing agent.
Prior to the present invention, it was not known or suspected that nerolidol, in combination with at least one quaternary ammonium compound, provides an antimicrobial composition with significantly enhanced antimicrobial efficacy as compared to prior antimicrobial compositions. Further, it was not known or suspected that nerolidol, when so used, allows for a reduction in the amount of quaternary ammonium compound which would otherwise be necessary for such antimicrobial efficacy.
It is an object of the present invention to provide an improved antimicrobial composition which shows enhanced antimicrobial efficacy. This and other objects are achieved by the present invention, which provides an improved antimicrobial composition by virtue of a nerolidol component. The nerolidol component is a surprisingly effective enhancer or potentiator of antimicrobial efficacy.
More particularly, it has been discovered that nerolidol significantly enhances the antimicrobial efficacy of a composition containing at least one quaternary ammonium compound. This enhanced anti-microbial efficacy is obtained with a surprisingly small amount of nerolidol.
That is, in standard tests for efficacy against various microorganisms, the inventive composition shows significantly reduced number of positive results as compared to a formulation containing a quaternary ammonium compound, but lacking nerolidol. These enhanced-efficacy results were obtained using minimal amounts of nerolidol, for example, 0.01 or 0.02 weight percent of the enhancer relative to the inventive composition.
In further efficacy tests, it was determined that nerolidol does not enhance the antimicrobial efficacy of a commercial pine cleaner formulation which does not contain a quaternary ammonium compound. It is theorized that nerolidol enhances or potentiates antimicrobial efficacy of the quaternary ammonium compound of the inventive composition, perhaps via synergism, although this invention is not in any way limited to this or any other theory.
As the nerolidol enhances antimicrobial efficacy, the amount of quaternary ammonium compound in the inventive composition may be much less than that used in prior compositions. For example, a typical prior art composition (not having the benefit of nerolidol) contains quaternary ammonium compounds in an amount more than about 1.1 weight percent relative to the composition. By contrast, in the present invention, positive results were obtained from efficacy tests performed with an inventive composition having reduced amounts of the quaternary ammonium compound, for example, 0.87 weight percent of such compound relative to the inventive composition.
The use of reduced amounts of quaternary ammonium compound constituents is important for environmental reasons, such as compliance with the standards of the U.S. Environmental Protection Agency for hard-surface disinfectants, and for consumer protection reasons, such as the reduction or elimination of skin or eye irritation which is particularly important for household cleaning compositions. Further, the use of reduced amounts of quaternary ammonium compound constituents improves the anti-filming and anti-streaking characteristics of the inventive compositions, which are particularly desirable in compositions for the cleaning of hard surfaces.
In summary, the test results evidence the significant enhanced antimicrobial efficacy of the inventive composition including at least one quaternary ammonium compound and nerolidol. This enhanced efficacy may be obtained using surprisingly small amounts of the enhancing or potentiating nerolidol. Further, this enhanced efficacy may be obtained using reduced amounts of quaternary ammonium compounds, as compared to amounts used in prior formulations.
Additional objects, advantages and features of the various aspects of the present invention will become apparent from the following description of its preferred embodiments.